Hydrostatic starter device of an internal combustion engine

Abstract

A hydrostatic starter device (10) for an internal combustion engine (2) having a hydrostatic power unit (11) connected with the output shaft (4) of the internal combustion engine (2) is driven with hydraulic fluid from a hydraulic fluid accumulator (12). The hydrostatic starter device (10) has an electrohydraulic charging device (30) to charge the hydraulic fluid accumulator (12) with hydraulic fluid and the hydrostatic power unit (11) is in a drive connection by a clutch device (25) with the internal combustion engine (2). The hydrostatic power unit (11) can be connected in a drive connection with the internal combustion engine (2) by the clutch device (25).

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims priority to German Patent Application No. DE 10 2012 108857.8 filed Sep. 20, 2012, which is herein incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to a hydrostatic starter device for an internal combustion engine to start the internal combustion engine from a stop. The starter device has a hydrostatic power unit that is in a drive connection with the output shaft of the internal combustion engine, is in communication with a hydraulic accumulator, and is driven with hydraulic fluid from the hydraulic fluid accumulator to start the internal combustion engine.[0004]2. Description of Related Art[0005]On internal combustion engines, such as diesel or gasoline engines, starter devices driven by an electric motor are generally used. To start the internal combustion engine, the speed of rotation necessary for the self-sustaining running of the ...

AI Technical Summary

Benefits of technology

[0011]The invention teaches that this object is accomplished in that the hydrostatic starter system has an electrohydraulic charging device to charge the hydraulic fluid accumulator with hydraulic fluid and the hydrostatic power unit is in a drive connection by a clutch device with the internal combustion engine. By means of the clutch device, the hydrostatic power unit is placed in a drive connection with the internal combustion engine for the starting process. With an electrohydraulic charging device, it can be ensured, with little extra construction effort or expense, that the hydraulic fluid accumulator is filled with hydraulic fluid prior to the starting process of the internal combustion engine so that, with the hydrostatic power unit, the internal combustion engine can be started under all operating conditions, even after being shut off for a relatively long time. An additional starter device driven by an electric motor with an electrical starter motor is, therefore, unnecessary. The electrohydraulic charging device can charge the hydraulic fluid accumulator over a longer period of time so that only a compact electrohydraulic charging device with a low delivery volume and a low output is necessary and can be driven by the existing electrical on-board power supply of the internal combustion engine. By means of the clutch device, the hydrostatic power unit, which preferably performs exclusively the function of a starter to start the shut-off internal combustion engine, can be connected with the output shaft of the internal combustion engine to start the internal combustion engine. After the starting process, when the internal combustion engine is running on its own, the drive connection with the output shaft can be disconnected so that with the starter device of the invention, after the starting process of the internal combustion engine has been completed, the hydrostatic power unit is still not being driven by the internal combustion engine. Thus, the idling losses during the operation of the internal combustion engine can be reduced. With the starter device of the invention, a rugged, fail-safe and economical starter system is provided, which makes possible a start-stop function of the internal combustion engine at brief intervals and results in low idling losses of the internal combustion engine.

[0012]With the electrohydraulic charging device, the hydraulic fluid accumulator can be charged even during operation and, thus, the hydraulic fluid accumulator can be charged when the internal combustion engine is running, thus ensuring the charging of the hydraulic fluid accumulator even before the internal combustion engine is shut off. In one particularly advantageous configuration of the invention, the hydraulic fluid accumulator can be charged when the internal combustion engine is shut off by means of the electrohydraulic charging device to a volume of hydraulic fluid, which is sufficient for the starting process of the internal combustion engine. It thereby becomes possible in a simple manner to ensure the charging of the accumulator under all operating conditions even when the internal combustion engine is shut off, and the internal combustion engine can be started with the hydrostatic power unit and, thus, the hydrostatic starter device.

[0013]In one preferred embodiment of the invention, the electrohydraulic charging device has a charging pump driven by an electric motor. The charging pump is connected on the input side with a reservoir and on the output side with the hydraulic fluid accumulator. A pressure relief valve is associated with the hydraulic fluid accumulator to protect the pressure in the hydraulic fluid accumulator. With a pressure relief valve associated with the hydraulic fluid accumulator, for example with a delivery line of the charging pump, it becomes possible in a simple manner to ensure that the hydraulic fluid accumulator is charged before the starting process of the internal combustion engine with a volume of hydraulic fluid which is sufficient for the starting process of the internal combustion engine because, during the charging process, the pressure generated by the electrohydraulic charging device can be set and secured.

Problems solved by technology

An additional starter device driven by an electric motor with an electrical starter motor is, therefore, unnecessary.

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